III-V FinFET CMOS with III-V and germanium-containing channel closely spaced

ABSTRACT

Closely spaced III-V compound semiconductor fins and germanium-containing semiconductor fins are provided by utilizing mandrel structures for III-V compound semiconductor material epitaxial growth and subsequent fin formation. Mandrel structures are formed on a semiconductor material stack that includes an uppermost layer of a relaxed germanium-containing material layer. A hard mask portion is formed on a pFET device region of the semiconductor material stack, and then recessed regions are provided in the relaxed germanium-containing material layer of the material stack semiconductor and in an nFET device region. An III-V compound semiconductor material plug is then formed in each recessed region. First sacrificial spacers are formed adjacent the sidewalls of each mandrel structures, and then each mandrel structure is removed. III-V compound semiconductor fins and germanium-containing semiconductor fins are then formed in the different device regions utilizing each first sacrificial spacer as an etch mask.

BACKGROUND

The present application relates to a semiconductor structure and amethod of forming the same. More particularly, the present applicationrelates to a method of forming a semiconductor structure includingclosely spaced III-V compound semiconductor fins andgermanium-containing fins.

For more than three decades, the continued miniaturization of metaloxide semiconductor field effect transistors (MOSFETs) has driven theworldwide semiconductor industry. Various showstoppers to continuedscaling have been predicated for decades, but a history of innovationhas sustained Moore's Law in spite of many challenges. However, thereare growing signs today that metal oxide semiconductor transistors arebeginning to reach their traditional scaling limits. Since it has becomeincreasingly difficult to improve MOSFETs and therefore complementarymetal oxide semiconductor (CMOS) performance through continued scaling,further methods for improving performance in addition to scaling havebecome critical.

The use of non-planar semiconductor devices such as, for example,semiconductor fin field effect transistors (finFETs) is the next step inthe evolution of complementary metal oxide semiconductor (CMOS) devices.Semiconductor fin field effect transistors (FinFETs) can achieve higherdrive currents with increasingly smaller dimensions as compared toconventional planar FETs.

Advanced hybrid channel finFETs containing both III-V compoundsemiconductor fins and germanium-containing semiconductor fins can bebeneficial for 7 nm and beyond technology. A practical problem offorming III-V nFETs and germanium-containing pFETs is how to form theIII-V compound semiconductor fins and germanium-containing semiconductorfins as close as possible to meet the ground rule requirement. Inconventional processing, the III-V compound semiconductor fins andgermanium-containing semiconductor fins are typically defined utilizingeither lithographic patterning or a sidewall image transfer process.Both of these patterning methods cannot achieve the ground rulerequirements for future technology nodes. As such, an alternative methodis needed to provide III-V compound semiconductor fins andgermanium-containing semiconductor fins that are closely spaced so as tomeet the ground rule requirements of future technology nodes.

SUMMARY

Closely spaced III-V compound semiconductor fins andgermanium-containing semiconductor fins are provided by utilizingmandrel structures for III-V compound semiconductor material epitaxialgrowth and subsequent fin formation. Mandrel structures are formed on asemiconductor material stack that includes an uppermost layer of arelaxed germanium-containing material layer. A hard mask portion isformed on a pFET device region of the semiconductor material stack, andthen recessed regions are provided in the relaxed germanium-containingmaterial layer of the material stack semiconductor and in an nFET deviceregion. An III-V compound semiconductor material plug is then formed ineach recessed region. First sacrificial spacers are formed adjacent thesidewalls of each mandrel structures, and then each mandrel structure isremoved. III-V compound semiconductor fins and germanium-containingsemiconductor fins are then formed in the different device regionsutilizing each first sacrificial spacer as an etch mask.

In one aspect of the present application, a method of forming asemiconductor structure is provided. In one embodiment of the presentapplication, the method includes providing a plurality of mandrelstructures on a relaxed germanium-containing material layer of asemiconductor material stack containing a pFET device region and an nFETdevice region. Recessed openings are then formed into the relaxedgermanium-containing material layer within the nFET device region of thesemiconductor material stack, but not the pFET device region. An III-Vcompound semiconductor material plug is then formed in each recessedopening. Next, sacrificial spacers are formed on sidewall surfaces ofeach mandrel structures within the pFET device region and the nFETdevice region. Each mandrel structure is then removed from the pFETdevice region and the nFET device region. Next, a plurality ofgermanium-containing semiconductor fins is formed in exposed portions ofthe relaxed germanium-containing material layer in the pFET deviceregion, and a plurality of III-V compound semiconductor fins is formedin exposed portions of the III-V compound semiconductor material plug inthe nFET device region utilizing the sacrificial spacers as an etchmask. The order of forming the semiconductor fins may vary.

In another aspect of the present application, a semiconductor structureis provided. In one embodiment of the present application, thesemiconductor structure includes a plurality of germanium-containingsemiconductor fins located in a pFET device region and separated fromeach other by a pitch. A plurality of III-V compound semiconductor finsis located in an nFET device region and separated from each other by thepitch. In accordance with the present application, a neighboring pair ofone germanium-containing fin of the plurality of germanium-containingsemiconductor fins and one III-V compound semiconductor fins of theplurality of III-V compound semiconductor fins is also separated by thepitch.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a cross sectional view illustrating an exemplary semiconductorstructure including a semiconductor material stack of, from bottom totop, a silicon material layer, an intermediate layer of germanium, and arelaxed germanium-containing material layer.

FIG. 2 is a cross sectional view of the exemplary semiconductorstructure of FIG. 1 after forming a mandrel material layer on thetopmost surface of the semiconductor material stack.

FIG. 3 is a cross sectional view of the exemplary semiconductorstructure of FIG. 2 after patterning the mandrel material layer toprovide a plurality of mandrel structures on the topmost surface of thesemiconductor material stack.

FIG. 4 is a cross sectional view of the exemplary semiconductorstructure of FIG. 3 after providing a hard mask material portioncovering a pFET device region of the semiconductor material stack, whileleaving an nFET device region of the semiconductor material stackexposed.

FIG. 5 is a cross sectional view of the exemplary semiconductorstructure of FIG. 4 after providing recessed openings extendingpartially through the germanium-containing material layer in the nFETdevice region utilizing each mandrel structure in the nFET device regionas an etch mask.

FIG. 6 is a cross sectional view of the exemplary semiconductorstructure of FIG. 5 after filling the openings within the nFET deviceregion with an III-V compound semiconductor material plug.

FIG. 7 is a cross sectional view of the exemplary semiconductorstructure of FIG. 6 after removing the hard mask material portion fromthe pFET device region, and forming a first sacrificial spacer onsidewall surfaces of each mandrel structure in the pFET device regionand the nFET device region.

FIG. 8 is a cross sectional view of the exemplary semiconductorstructure of FIG. 7 after removing each mandrel structure from the pFETdevice region and the nFET device region.

FIG. 9 is a cross sectional view of the exemplary semiconductorstructure of FIG. 8 after forming a first block mask covering the pFETdevice region.

FIG. 10 is a cross sectional view of the exemplary semiconductorstructure of FIG. 9 after forming a plurality of III-V compoundsemiconductor fins within the nFET device region.

FIG. 11 is a cross sectional view of the exemplary semiconductorstructure of FIG. 10 after removing the first block mask from the pFETdevice region, and providing a second block mask covering the nFETdevice region.

FIG. 12 is a cross sectional view of the exemplary semiconductorstructure of FIG. 11 after forming a plurality of germanium-containingfins within the pFET device region.

FIG. 13 is a cross sectional view of the exemplary semiconductorstructure of FIG. 12 after removing the second block mask from the nFETdevice region.

FIG. 14 is a cross sectional view of the exemplary semiconductorstructure of FIG. 13 after forming local fin isolation structuresbetween each germanium-containing semiconductor fin within the pFETdevice region and between each III-V compound semiconductor fin withinthe nFET device region.

FIG. 15 is a cross sectional view of the exemplary semiconductorstructure of FIG. 14 after forming a functional gate structurestraddling each germanium-containing semiconductor fin within the pFETdevice region and each III-V compound semiconductor fin within the nFETdevice region.

FIG. 16 is a cross sectional view of the exemplary semiconductorstructure of FIG. 13 after forming a second sacrificial spacer onsidewall surfaces of each germanium-containing semiconductor fin withinthe pFET device region and on sidewall surfaces of each III-V compoundsemiconductor fin within the nFET device region.

FIG. 17A is a top-down view of the exemplary semiconductor structure ofFIG. 16 after forming an anchoring structure, and after performing anetch to undercut each germanium-containing semiconductor fin within thepFET device region and each III-V compound semiconductor fin within thenFET device region.

FIG. 17B is a cross sectional view of the exemplary semiconductorstructure of FIG. 17A.

FIG. 18 is a cross sectional view of the exemplary semiconductorstructure of FIGS. 17A-17B after forming an isolation structure in theundercut area located beneath each germanium-containing semiconductorfin within the pFET device region and each III-V compound semiconductorfin within the nFET device region.

FIG. 19 is a cross sectional view of the exemplary semiconductorstructure of FIG. 18 after removing each second sacrificial spacer.

FIG. 20 is a cross sectional view of the exemplary semiconductorstructure of FIG. 19 after removing a remaining portion of the firstsacrificial spacer from atop each germanium-containing semiconductor finwithin the pFET device region and from atop each III-V compoundsemiconductor fin within the nFET device region, and forming afunctional gate structure straddling each germanium-containingsemiconductor fin within the pFET device region and each III-V compoundsemiconductor fin within the nFET device region.

FIG. 21 is a cross sectional view of the exemplary semiconductorstructure of FIG. 8 after forming another block mask at a boundarybetween the pFET device region and the nFET device region, and thenforming a plurality of germanium-containing fins within the pFET deviceregion and a plurality of III-V compound semiconductor fins in the nFETdevice region.

DESCRIPTION

The present application will now be described in greater detail byreferring to the following discussion and drawings that accompany thepresent application. It is noted that the drawings of the presentapplication are provided for illustrative purposes only and, as such,the drawings are not drawn to scale. It is also noted that like andcorresponding elements in the various embodiments of the presentapplication are referred to by like reference numerals.

In the following description, numerous specific details are set forth,such as particular structures, components, materials, dimensions,processing steps and techniques, in order to provide an understanding ofthe various embodiments of the present application. However, it will beappreciated by one of ordinary skill in the art that the variousembodiments of the present application may be practiced without thesespecific details. In other instances, well-known structures orprocessing steps have not been described in detail in order to avoidobscuring the present application.

As mentioned above, prior art processes provide III-V compoundsemiconductor fins and germanium-containing semiconductor fins that arenot closely spaced (typically the spacing is not at pitch, but multipleof a pitch or even larger) thus the prior art processes cannot meet theground rule requirement of future technology nodes. The presentapplication provides a method of forming III-V compound semiconductorfins (for nFET devices) and germanium-containing semiconductor fins (forpFET devices) that are closely spaced (i.e., at fin pitch, which is20-100 nm from each other) and thus solves the problem mentioned abovewith prior art processes. Notably, closely spaced III-V compoundsemiconductor fins and germanium-containing semiconductor fins can beachieved in the present application by using sacrificial mandrelstructures not only for fin formation, but also for III-V compoundsemiconductor material epitaxial growth. In addition to providingclosely spaced III-V compound semiconductor fins (for nFET devices) andgermanium-containing semiconductor fins (for pFET devices), the presentapplication can also, in some embodiments, completely eliminate theformation of epitaxial defects at the trench edges.

Referring first to FIG. 1, there is illustrated an exemplarysemiconductor structure including a semiconductor material stack 10 of,from bottom to top, a silicon material layer 12L, an intermediate layerof germanium 14L, and a relaxed germanium-containing material layer 16Lthat can be employed in an embodiment of the present application.

The term “silicon material layer” is used throughout the presentapplication to denote a material layer that is comprised of unalloyed,i.e., pure, silicon. In one embodiment of the present application, thesilicon material layer 12L may be comprised of single crystallinesilicon. The silicon material layer 12L may be a relaxed silicon layer.The term “relaxed” is used throughout the present application to denotea material layer having no strain or a strain value that is less than0.3%. In one embodiment of the present, the silicon material layer 12Lof the material stack 10 may be a bulk silicon substrate. In anotherembodiment of the present application, the silicon material layer 12 maybe a topmost surface of a silicon-on-insulator substrate which includesa buried insulator material and a handle substrate beneath the siliconmaterial layer 12L.

The intermediate layer of germanium 14L, which has a bottommost surfacein direct contact with a topmost surface of the silicon material layer12L, is a contiguous layer that covers the entire topmost surface of thesilicon material layer 12L. The intermediate layer of germanium 14L iscomprised entirely of germanium. In one embodiment of the presentapplication, the intermediate layer of germanium 14L can have athickness from 100 nm to 10000 nm. In another embodiment of the presentapplication, the intermediate layer of germanium 14L can have athickness from 1000 nm to 5000 nm. Other thicknesses that are greaterthan or lesser than the aforementioned thickness ranges can also beemployed for the intermediate layer of germanium 14L.

The relaxed germanium-containing material layer 16L, which has abottommost surface in direct contact with a topmost surface of theintermediate layer of germanium 14L, is also a contiguous layer thatcovers the entire topmost surface of the intermediate layer of germanium14L. The term “germanium-containing material” is used throughout thepresent application to denote unalloyed, i.e., pure, germanium, or asilicon germanium alloy having a germanium content of from 20 atomic %to 99 atomic %. The relaxed germanium-containing material layer 16Lincludes an upper portion that has fewer defects than a lower portionthat is present at the interface with the underlying intermediate layerof germanium 14L. In one embodiment of the present application, therelaxed germanium-containing material layer 16L can have a thicknessfrom 100 nm to 10000 nm. In another embodiment of the presentapplication, the relaxed germanium-containing material layer 16L canhave a thickness from 1000 nm to 5000 nm. Other thicknesses that aregreater than or lesser than the aforementioned thickness ranges can alsobe employed for the relaxed germanium-containing material layer 16L solong as the germanium-containing material layer 16L remains relaxed.

The semiconductor material stack 10 shown in FIG. 1 can be formed byfirst providing the silicon material layer 12L. The silicon materiallayer 12L can be provided by techniques that are well known to thoseskilled in the art. After providing the silicon material layer 12L, theintermediate layer of germanium 14L and the relaxed germanium-containingmaterial layer 16L can be formed by epitaxial deposition. In someembodiments of the present application, the intermediate layer ofgermanium 14L and the relaxed germanium-containing material layer 16Lcan be formed without breaking vacuum between the various epitaxialdeposition steps. In yet other embodiments, the vacuum is broken betweenthe epitaxial deposition of the intermediate layer of germanium 14L andepitaxial deposition of the relaxed germanium-containing material layer16L.

The terms “epitaxial growth and/or deposition” and “epitaxially formedand/or grown” are used throughout the present application to denote thegrowth of a semiconductor material on a deposition surface of asemiconductor material, in which the semiconductor material being grownhas the same crystalline characteristics as the semiconductor materialof the deposition surface. Thus, in this instance, the intermediatelayer of germanium 14L has an epitaxial relationship, i.e., same crystalorientation, with the underlying silicon material layer 12L, and therelaxed germanium-containing material layer 16L has an epitaxialrelationship with the underlying intermediate layer of germanium 14L.

In an epitaxial deposition process, the chemical reactants provided bythe source gases are controlled and the system parameters are set sothat the depositing atoms arrive at the deposition surface of asemiconductor material with sufficient energy to move around on thesurface and orient themselves to the crystal arrangement of the atoms ofthe deposition surface. Therefore, an epitaxial semiconductor materialthat is formed by an epitaxial deposition process has the samecrystalline characteristics as the deposition surface on which it isformed. For example, an epitaxial semiconductor material deposited on a{100} crystal surface will take on a {100} orientation.

Examples of various epitaxial growth process apparatuses that aresuitable for use in the present application include, e.g., rapid thermalchemical vapor deposition (RTCVD), low-energy plasma deposition (LEPD),ultra-high vacuum chemical vapor deposition (UHVCVD), atmosphericpressure chemical vapor deposition (APCVD) and molecular beam epitaxy(MBE). The temperature for epitaxial deposition typically ranges from550° C. to 900° C. Although higher temperature typically results infaster deposition, the faster deposition may result in crystal defectsand film cracking. In some embodiments of the present application, andduring the epitaxial growth of the relaxed germanium-containing materiallayer 16L, intermediate annealing steps may be performed to ensure thatat least the uppermost portion of layer 16L is relaxed and to trap anydefects in the lower portion of layer 16L. When employed, eachintermediate anneal is performed in an inert ambient such a helium,argon, neon, or mixtures thereof. In some embodiments, the intermediateanneals can be performed in hydrogen. Also, each intermediate anneal isperformed at a temperature from 600° C. to 950° C.

A number of different germanium source gases may be used for thedeposition of the intermediate layer of germanium 14L. In someembodiments, the source gas for the deposition of the intermediate layerof germanium 14L may include germane, digermane, halogermane,dichlorogermane, trichlorogermane, tetrachlorogermane and combinationsthereof. Carrier gases like hydrogen, nitrogen, helium and argon can beused.

A number of different source gases may be used in forming the relaxedgermanium-containing material layer 16L. When the relaxedgermanium-containing material layer 16L is comprised of unalloyedgermanium, one of the germanium source gases mentioned above inproviding the intermediate layer of germanium 14L can be employed. Insome embodiments of the present application, a same germanium source gasis used in providing both the intermediate layer of germanium 14L andthe relaxed germanium-containing material layer 16L. When the relaxedgermanium-containing material layer 16L is comprised of a silicongermanium alloy, the relaxed germanium-containing material layer 16L canbe formed utilizing a combination of a silicon source gas and agermanium source gas. Examples of a silicon source include silane,disilane, trisilane, tetrasilane, hexachlorodisilane, tetrachlorosilane,dichlorosilane, trichlorosilane, methylsilane, dimethylsilane,ethylsilane, methyldisilane, dimethyldisilane, hexamethyldisilane andcombinations thereof. Examples of a germanium source include germane,digermane, halogermane, dichlorogermane, trichlorogermane,tetrachlorogermane and combinations thereof. In some embodiments, asource gas including a combination of a silicon source material and agermanium source material may be used in providing a relaxedgermanium-containing material layer 16L comprised of a silicon germaniumalloy material. Carrier gases like hydrogen, nitrogen, helium and argoncan also be used to form the relaxed germanium-containing material layer16L.

Referring now to FIG. 2, there is illustrated the exemplarysemiconductor structure of FIG. 1 after forming a mandrel material layer18L on the topmost surface of the semiconductor material stack 10L. Inthe present application, the mandrel material layer 18L is formeddirectly on a topmost surface of the relaxed germanium-containingmaterial layer 16L. As is shown, the mandrel material layer 18L is acontiguous layer that covers the entire topmost surface of the relaxedgermanium-containing material layer 16L.

The mandrel material layer 18L can include any material (semiconductor,dielectric or conductive) that can be selectively removed from thestructure during a subsequently performed etching process. A singlematerial can be used in providing the mandrel material layer 18L, or amultilayered stack of materials can be used in providing the mandrelmaterial layer 18L. In one embodiment, the mandrel material layer 18Lmay be composed of polysilicon. In another embodiment, the mandrelmaterial layer 18L may be composed of amorphous carbon. In yet a furtherembodiment, the mandrel material layer 18L may be composed of a metalsuch as, for example, Al, W, or Cu. The mandrel material layer 18L canbe formed by a deposition process such as, for example, by chemicalvapor deposition or plasma enhanced chemical vapor deposition. Thethickness of mandrel material layer 18L can be from 50 nm to 300 nm,although lesser and greater thicknesses can also be employed.

Referring now to FIG. 3, there is illustrated the exemplarysemiconductor structure of FIG. 2 after patterning the mandrel materiallayer 18L to provide a plurality of mandrel structures 18P on thetopmost surface, i.e., the germanium-containing material layer 16L, ofthe semiconductor material stack 10. The patterning of the mandrelmaterial layer 18L can be performed by lithography and etching.Lithography can include forming a photoresist material above the mandrelmaterial layer 18L, exposing the photoresist material to a desiredpattern of radiation and developing the photoresist utilizing aconventional photoresist developer. After the photoresist material hasbeen patterned, the pattern provided to the photoresist material can betransferred to the underlying mandrel material layer 18L by etching. Inone embodiment, the etch used for pattern transfer may be a dry etchingprocess such as, for example, reactive ion etching, plasma etching, ionbeam etching or laser ablation. In another embodiment, the etch used forthe pattern transfer may include a chemical wet etchant that isselective in removing the exposed portions of the mandrel material layer18L.

In the embodiment that is illustrated in FIG. 3, each mandrel structure18P that is formed has a constant width and is spaced apart from aneighboring mandrel structure by a constant pitch. In one embodiment,the width of each mandrel structure 18P, as measured from one sidewallsurface to an opposing sidewall surface, is from 30 nm to 60 nm,although lesser and greater widths can also be employed.

Referring now to FIG. 4, there is illustrated the exemplarysemiconductor structure of FIG. 3 after providing a hard mask materialportion 20P covering a pFET device region 22 of the semiconductormaterial stack 10, while leaving an nFET device region 24 of thesemiconductor material stack 10 exposed. As is shown, the hard maskportion 20P covers the mandrel structures 18P that are positioned in thepFET device region 22. When a mandrel structure is present at theboundary between the pFET device region 22 and the nFET device region24, as is the case with the middle mandrel structure shown in FIG. 4,the hard mask material portion 20P is present only on portions of themandrel structure that are present in the pFET device region 22.

The hard mask material portion 20P comprises a hard mask material. Whenthe mandrel material layer 18L is comprised of a dielectric material,then the hard mask material that provides the hard mask material portion20P comprises a different dielectric material than the dielectricmaterial used to provide the mandrel material layer 18L. The hard maskmaterial that can be used in providing the hard mask material portion20P may include a semiconductor oxide, a semiconductor nitride and/or asemiconductor oxynitride. In one embodiment, the hard mask material thatcan be used in providing the hard mask material portion 20P can becomprised of silicon dioxide. In another embodiment, the hard maskmaterial that can be used in providing the hard mask material portion20P can be comprised of silicon nitride. In yet another embodiment, thehard mask material that can be used in providing the hard mask materialportion 20P can be a stack comprised of, in any order, silicon dioxideand silicon nitride. The thickness of the hard mask material that can beused in providing the hard mask material portion 20P can range from 2 nmto 10 nm, with a thickness from 3 nm to 6 nm being more typical.

In one embodiment of the present application, the hard mask materialportion 20P can be formed by providing a hard mask material on theexposed topmost surface of the exemplary semiconductor structure shownin FIG. 3, and then patterning the hard mask material by lithography andetching. In another embodiment, the hard mask portion 20P can be formedby first providing a block mask protecting the nFET device region 24,the hard mask material is then provided to the pFET device region 22,and thereafter the block mask is removed from the nFET device region 24.

Notwithstanding which technique is employed in forming the hard maskmaterial portion 20P, the hard mask material that can be used inproviding the hard mask material portion 20P can be formed by adeposition process such as, for example, chemical vapor deposition (CVD)or plasma enhanced chemical vapor deposition (PECVD).

Referring now to FIG. 5, there is illustrated the exemplarysemiconductor structure of FIG. 4 after providing recessed openings,i.e., trenches, 26 extending partially through the relaxedgermanium-containing material layer 16L in the nFET device region 24utilizing each mandrel structure 18P in the nFET device region 24 as anetch mask. Since the hard mask material portion 20P covers the pFETdevice region 22, no material removal occurs in the pFET device region22. The remaining portion of the relaxed germanium-containing materiallayer 16L can now be referred to as a “germanium-containing materialportion 16P.

The recessed openings, i.e., trenches, 26 which extend partially throughthe germanium-containing material layer 16L in the nFET device region 24expose a sub-surface 16S of the relaxed germanium-containing materiallayer 16L in the nFET device region 24. The term “sub-surface” is usedthroughout the present application to denote a surface of a materiallayer that is below the original topmost surface of the material layer.In one embodiment of the present application, each recessed opening 26that is formed has a depth, as measured from the original topmostsurface of the relaxed germanium-containing material layer 16L to theexposed sub-surface 16S, of from 100 nm to 2000 nm. Other depths arepossible as long as the bottommost surface of each recessed opening doesnot directly contact the underlying intermediate layer of germanium 14L.

The recessed openings 26 which extend partially through the relaxedgermanium-containing material layer 16L in the nFET device region 24 canbe formed utilizing an etching process that is selective in removing therelaxed germanium-containing material layer 16L relative to thematerials that provide the hard mask material portions 20P and themandrel structure 18P. In one embodiment of the present application, theetching used to provide the recessed openings 26 within the nFET deviceregion 24 comprises an anisotropic etch such as, for example, reactiveion etching. When an anisotropic etch is employed in providing therecessed openings 26, the sidewall surfaces of the recessed openings 26would be vertical coincident to the sidewall surfaces of the overlyingmandrel structures 18P.

In some embodiments (and as shown in the drawing), a portion of therelaxed germanium-containing material layer 16P that is present beneaththe overlying mandrel structures 18P in the nFET device region 24 can belaterally etched to provide recessed openings 26 whose sidewall surfaces28 undercut the overlying mandrel structures 18P. In one embodiment ofthe present application, such recessed openings 26 can be formed byperforming a lateral pull back etch during the etch that provides therecessed openings 26. In another embodiment of the present application,the lateral pull back etch can be performed after an initial etch thatprovides recessed openings 26 having sidewall surfaces that arevertically coincident to the sidewall surfaces of the overlying mandrelstructures 18P. For example, an isotropic etch can be used to providethe recessed openings 26 having sidewall surfaces 28 as shown in FIG. 5.

Referring to FIG. 6, there is illustrated the exemplary semiconductorstructure of FIG. 5 after filling the recessed openings 26 within thenFET device region 24 with an III-V compound semiconductor material plug30. The III-V compound semiconductor material plug 30 completely fillseach recessed opening 26. The III-V compound semiconductor material plug30 has a bottommost surface that directly contacts the exposedsub-surface 16S of the relaxed germanium-containing material portion16P. The III-V compound semiconductor material plug 30 has a topmostsurface that is typically coplanar with a topmost surface of the relaxedgermanium-containing material portion 16P. In some embodiments (notshown), the topmost surface of the III-V compound semiconductor materialplug 30 extends above the topmost surface of the relaxedgermanium-containing material portion 16P. In other embodiments, and asshown, a portion of the topmost surface of the III-V compoundsemiconductor material plug 30 directly contacts a bottommost surface ofthe mandrel structures 18P in the nFET device region 24.

The III-V compound semiconductor material plug 30 includes at least oneIII-V compound semiconductor material that contains at least one elementfrom Group IIIA of the Periodic Table of Elements and at least oneelement from Group VA of the Periodic Table of Elements. For example,the III-V compound semiconductor material plug 30 can comprise GaAs,InP, InAs, and GaInP. In some embodiments of the present application(and as shown in FIG. 6), the III-V compound semiconductor material plug30 may include a single III-V compound semiconductor material. In otherembodiments of the present application (not shown), the III-V compoundsemiconductor material plug 30 may include two or more III-V compoundsemiconductor material stacked one atop the other.

The III-V compound semiconductor material that provides the III-Vcompound semiconductor material plug 30 can be formed utilizing anepitaxial deposition process as described above in forming theintermediate layer of germanium 14L and the relaxed germanium-containingmaterial layer 16L. Since an epitaxial deposition process is used informing the III-V compound semiconductor material that provides theIII-V compound semiconductor material plug 30, the III-V compoundsemiconductor material plug 30 has an epitaxial relationship with theexposed sub-surface 16S of the relaxed germanium-containing materialportion 16P.

In some embodiments, the epitaxial deposition of the III-V compoundsemiconductor material that provides the III-V compound semiconductormaterial plug 30 can be performed utilizing one of the epitaxialdeposition apparatuses mentioned and the conditions for epitaxialgrowing the III-V compound semiconductor material that provides theIII-V compound semiconductor material plug 30 can be the same as thosementioned above in forming the intermediate layer of germanium 14L andthe relaxed germanium-containing material layer 16L. The III-V compoundsemiconductor material that provides the III-V compound semiconductormaterial plug 30 can be formed utilizing any well known source gas(es)that is(are) typically used in epitaxially growing a III-V compoundsemiconductor material.

In other embodiments, the epitaxial deposition of the III-V compoundsemiconductor material that provides the III-V compound semiconductormaterial plug 30 can include an epitaxial semiconductor regrowth processsuch as is described, for example, in U.S. Patent ApplicationPublication No. 2011/0049568 to Lochtefeld et al., the entire contentand disclosure of which is incorporated herein by reference. Thisepitaxial semiconductor regrowth may be referred to herein as an aspectratio trapping process. In the present application, the aspect ratiotrapping process typically works better when the aspect ratio (trenchdepth to trench width) of the trench is at least 1:2. When an aspectratio trapping process is employed, the III-V compound semiconductormaterial plug 30 may include a lower portion having a first defectdensity and an upper portion having a second defect density that is lessthan the first defect density.

In some embodiments of the present application and when aspect ratiotrapping is employed, the selected crystallographic direction of theIII-V compound semiconductor material that provides the III-V compoundsemiconductor material plug 30 is aligned with at least one propagationdirection of threading dislocations in the recessed opening 26 in whicheach III-V compound semiconductor material plug 30 is formed. Threadingdislocations in this region may substantially terminate at the sidewallof the neighboring relaxed germanium-containing material 16P. In oneembodiment of the present application, the selected crystallographicdirection of the sub-surface 16S of the relaxed germanium-containingmaterial portion 16P is aligned with direction of propagation ofthreading dislocations in the III-V compound semiconductor material thatprovides the III-V compound semiconductor material plug 30. In certainembodiments, the orientation angle ranges from about 30 to about 60degrees, for example, is about 45 degrees to such crystallographicdirection. The surface of the sub-surface 16S of the relaxedgermanium-containing material portion 16P may have a (100), (110), or(111) crystallographic orientation. In some embodiments, the selectedcrystallographic direction is substantially aligned with a <110>crystallographic direction of the sub-surface 16S of the relaxedgermanium-containing material portion 16P.

In some embodiments of the present application, a planarization processsuch as, for example, an etch back process, follows the epitaxialdeposition of the III-V compound semiconductor material that providesthe III-V compound semiconductor material plug 30.

Referring now to FIG. 7, there is illustrated the exemplarysemiconductor structure of FIG. 6 after removing the hard mask materialportion 20P from the pFET device region 22, and forming a firstsacrificial spacer 32 on sidewall surfaces of each mandrel structure 18Pin the pFET device region 22 and the nFET device region 24.

The hard mask material portion 20P can be removed from the structureutilizing an etching process that selectively removes the hard maskmaterial that provides the hard mask material portion 20P as compared tothe material of the mandrel structure, the relaxed germanium-containingmaterial portion 16P, and the III-V compound semiconductor material plug30. The removal of the hard mask material portion 20P exposes the pFETdevice region 22 for further processing.

After removing the hard mask material portion 20P from the pFET deviceregion 22, first sacrificial spacers 32 are formed on the exposedsidewall surfaces of each mandrel structure 18P. As is shown, each firstsacrificial spacer 32 has a topmost surface that is coplanar with atopmost surface of each mandrel structure 18P. As is also shown, some ofthe first sacrificial spacers 32 have a bottommost surface locateddirectly on a topmost surface of the relaxed germanium-containingmaterial portion 16P, while other first sacrificial spacers 32 have abottommost surface located directly on a topmost surface of one of theIII-V compound semiconductor material plugs 30. Each first sacrificialspacer 32 has a width that is less than a width of each mandrelstructure 18P. Typically, each first sacrificial spacer 32 has a width,as measured from one sidewall surface to an opposing, sidewall surface,of from 4 nm to 20 nm. It is noted that the width of the firstsacrificial spacer 32 defines the width of each semiconductor fin to besubsequently formed.

Each first sacrificial spacer 32 may comprise a first dielectric spacermaterial that has a different etching characteristics compared to thematerial of the mandrel structures 18P. In one embodiment of the presentapplication, each first sacrificial spacer 32 may include a nitride suchas silicon nitride, an oxide such as silicon dioxide, or an oxynitridesuch as silicon oxynitride. In another embodiment of the presentapplication, the dielectric material that is used in providing eachfirst sacrificial spacer 32 may be a dielectric material having adielectric constant of less than silicon dioxide (such dielectricmaterials may be referred to herein as low k). Examples of dielectricmaterials having a low dielectric constant include, but are not limitedto, silsesquioxanes, C-doped oxides (i.e., organic silicates) thatinclude atoms of Si, C, O and H, and thermosetting polyarylene ethers.The term “polyarylene” is used throughout the present application todenote aryl moieties or inertly substituted aryl moieties which arelinked together by bonds, fused rings, or inert linking groups such as,for example, oxygen, sulfur, sulfone, sulfoxide, carbonyl and the like.In yet another embodiment of the present application, the dielectricmaterial that is used in providing each first sacrificial spacer 32 maybe a dielectric material having a dielectric constant that is equal toor even greater than that of silicon dioxide (such dielectric materialsmay be referred to herein as high k). Examples of high k dielectricmaterials include, for example, a dielectric metal oxide such as, forexample, HfO₂, ZrO₂, La₂O₃, Al₂O₃, TiO₂, SrTiO₃, LaAlO₃, Y₂O₃,HfO_(x)N_(y), ZrO_(x)N_(y), La₂O_(x)N_(y), Al₂O_(x)N_(y), TiO_(x)N_(y),SrTiO_(x)N_(y), LaAlO_(x)N_(y), Y₂O_(x)N_(y), SiON, SiN_(x), a silicatethereof, and an alloy thereof. Each value of x is independently from 0.5to 3 and each value of y is independently from 0 to 2.

Each first sacrificial spacer 32 may be formed by first conformallydepositing a dielectric spacer material layer over each mandrelstructure 18P, over exposed topmost surfaces of the relaxedgermanium-containing material portion 16P and over exposed topmostsurfaces of each III-V compound semiconductor material plug 30. Afterdepositing the dielectric spacer material layer, the dielectric spacermaterial layer can be anisotropically etched to remove horizontalportions of the dielectric spacer material layer forming the firstsacrificial spacers 32 shown in FIG. 7.

Referring now to FIG. 8, there is illustrated the exemplarysemiconductor structure of FIG. 7 after removing each mandrel structure18P from the pFET device region 22 and the nFET device region 24, whilemaintaining the first sacrificial spacers 32 on the exposed topmostsurfaces of the relaxed germanium-containing material portion 16P andthe exposed topmost surfaces of each III-V compound semiconductormaterial plug 30. Each mandrel structure 18P can be removed utilizing anetching process that is selective in removing the material that provideseach mandrel structure 18P as compared to the dielectric spacer materialthat provides each first sacrificial spacer 32. The etch process thatcan be used to remove each mandrel structure 18P can be an anisotropicor an isotropic etch. As is shown in FIG. 8, each first sacrificialspacer 32 is uniformly spaced apart by a width, w, which is equal to thewidth of the mandrel structure 18P.

Referring now to FIG. 9, there is illustrated the exemplarysemiconductor structure of FIG. 8 after forming a first block mask 34covering the pFET device region 22, while leaving the nFET device region24 exposed for further processing. The first block mask 34 may be aphotoresist material, a hard mask material (having a compositiondifferent from the first sacrificial spacer 32), or a multilayeredcombination thereof. The first block mask can be formed by deposition ofa block mask material, followed by lithography and optionally etching.

Referring now to FIG. 10, there is illustrated the exemplarysemiconductor structure of FIG. 9 after forming a plurality of III-Vcompound semiconductor fins 36 within the nFET device region 24. Theplurality of III-V compound semiconductor fins 36 is formed by removingexposed portions of each the III-V compound semiconductor material plug30 not protected by the first sacrificial spacers 32. The removal of theexposed portions of each the III-V compound semiconductor material plug30 not protected by the first sacrificial spacers 32 can be performedutilizing an anisotropic etching process such as, for example, reactiveion etching. In some embodiments (and as shown), the etch stops onsub-surface 16S of the relaxed germanium-containing material portion16P. In other embodiment this etch may stop at the bottommost surface ofthe III-V compound semiconductor material plug 30 or even somewhere inthe III-V compound semiconductor material plug 30. During this etch, anupper portion of the first sacrificial spacers 32 within the nFET deviceregion 24 can be removed.

Each III-V compound semiconductor fin 36 comprises a remaining portionof the III-V compound semiconductor material plug 30. Each III-Vcompound semiconductor fin 36 can be capped with a remaining portion ofthe first sacrificial spacer 32. The remaining portion of firstsacrificial spacer 32 can be referred to herein as a first sacrificialcap portion 32P. As used herein, a “fin” refers to a contiguousstructure including a semiconductor material and including a pair ofvertical sidewalls that are parallel to each other. As used herein, asurface is “vertical” if there exists a vertical plane from which thesurface does not deviate by more than three times the root mean squareroughness of the surface.

Referring now to FIG. 11, there is illustrated the exemplarysemiconductor structure of FIG. 10 after removing the first block mask34 from the pFET device region 22, and providing a second block mask 38covering each III-V compound semiconductor fin 36 in the nFET deviceregion 24. The removal of the first block mask 34 can be performed byeither a conventional resist stripping process and/or by utilizing anetch that is selective in removing the material of the first block mask34. The second block mask 38 can include one of the block mask materialsmentioned above for the first block mask 34. The second block mask 38can be formed utilizing the technique mentioned above in forming thefirst block mask 34. The second block mask 38 covers the entirely of theIII-V semiconductor fins 36 within the nFET device region 24.

Referring now to FIG. 12, there is illustrated the exemplarysemiconductor structure of FIG. 11 after forming a plurality ofgermanium-containing semiconductor fins 40 within the pFET device region22. The plurality germanium-containing semiconductor fins 40 is formedby removing exposed portions of each the relaxed germanium-containingmaterial portion 16P not protected by the first sacrificial spacers 32.The removal of the exposed portions of each the relaxedgermanium-containing material portion 16P not protected by the firstsacrificial spacers 32 can be performed utilizing an anisotropic etchingprocess such as, for example, reactive ion etching. The etch stop onanother sub-surface of the relaxed germanium-containing material portion16P. In some embodiments (and as shown), the another sub-surface iscoplanar with sub-surface 16S. In other embodiments (not shown), theanother sub-surface exposed in the pFET device region 22 can locatedabove or located beneath the sub-surface 16S exposed in the nFET deviceregion 24. During this etch, an upper portion of the first sacrificialspacers 32 within the pFET device region 22 can be removed.

Each germanium-containing semiconductor fin 40 comprises a remainingportion of the relaxed germanium-containing material portion 16P. Eachgermanium-containing semiconductor fin 40 can be capped with a remainingportion of the first sacrificial spacer 32. The remaining portion offirst sacrificial spacer 32 can be referred to herein as a firstsacrificial cap portion 32P.

Referring now to FIG. 13, there is illustrated the exemplarysemiconductor structure of FIG. 12 after removing the second block mask38 from the nFET device region 24. The removal of the second block mask38 can be performed by either a conventional resist stripping processand/or by utilizing an etch that is selective in removing the materialof the second block mask 38.

In some embodiments and as shown, each of the germanium-containingsemiconductor fins 40 has a topmost surface that is co-planar with atopmost surface of each of the III-V compound semiconductor fins 36. Inother embodiments (not shown), each of the germanium-containingsemiconductor fins 40 has a topmost surface that is located above orbeneath a topmost surface of each of the III-V compound semiconductorfins 36.

As is shown in FIG. 13, each of the germanium-containing semiconductorfins 40 and each of the III-V compound semiconductor fins 36 are spacedat a first pitch, p. Also, and as shown in FIG. 13, the nearestneighboring pair of germanium-containing semiconductor fin 40 and III-Vcompound semiconductor fin 36 is spaced at the same pitch (i.e., thefirst pitch) as the pitch between individual same semiconductor materialfins. The pitch can be between 20 nm and 100 nm. In the presentapplication, the pitch (i.e. first pitch) is defined as the spacebetween fin plus fin width.

It is noted that although the present application describes andillustrates the formation of the III-V compound semiconductor fins 36 inthe nFET device region 24 prior to forming the germanium-containingsemiconductor fin 40 in the pFET device region 22, the presentapplication also works when the germanium-containing semiconductor fins40 are formed prior to forming the III-V compound semiconductor fins 36.In such an embodiment, the order of block mask formation and fin etchingdescribed above would be reversed.

Referring now to FIG. 14, there is illustrated the exemplarysemiconductor structure of FIG. 13 after forming local fin isolationstructures 42 between each germanium-containing semiconductor fin 40within the pFET device region 22 and between each III-V compoundsemiconductor fin 36 within the nFET device region 24. In someembodiments, and during the formation of the local fin isolationstructures 42, the remaining portion of the first sacrificial spacer 32Pcan be removed from atop each germanium-containing semiconductor fin 40within the pFET device region 22 and atop each III-V compoundsemiconductor fin 36 within the nFET device region 24. In anotherembodiment of the present application, the remaining portion of thefirst sacrificial spacer 32P is not removed from atop eachgermanium-containing semiconductor fin 40 within the pFET device region22 and atop each III-V compound semiconductor fin 36 within the nFETdevice region 24. In such an embodiment, the remaining portion of thefirst sacrificial spacer 32P serves as fin cap.

The local fin isolation structure 42 can be formed by first filling thespaces between each semiconductor fin with a dielectric oxide materialsuch as, for example, silicon dioxide. In some embodiments, aplanarization process such as, for example, chemical mechanicalplanarization follows the deposition of the dielectric oxide material.When employed, the planarization process removes any dielectric oxidematerial that is present above the semiconductor fins 36, 40. Theplanarization process can also remove the remaining portion of the firstsacrificial spacer 32P from each semiconductor fin 36, 40. An etch backprocess can then be employed to recess the dielectric oxide materialbelow the topmost surface of each semiconductor fin 36, 40 forming eachlocal isolation structure 42 shown in FIG. 14.

Each local fin isolation structure 42 that is formed has a topmostsurface that is vertically offset and located beneath the topmostsurface of each semiconductor fin 36, 40. Each local fin isolationstructure 42 is present at the footprint of a semiconductor fin 36, 40and has a thickness from 20 nm to 200 nm. A bottommost surface of eachlocal fin isolation structure 42 is present on a surface of theremaining germanium-containing semiconductor portion 16P.

Referring now to FIG. 15, there is illustrated the exemplarysemiconductor structure of FIG. 14 after forming a functional gatestructure (44, 46) straddling each germanium-containing semiconductorfin 40 within the pFET device region 22 and each III-V compoundsemiconductor fin 36 within the nFET device region 24. Although a singlefunctional gate structure (44, 46) is described and illustrated in thedrawing, a plurality of functional gate structures can be formed. By“straddling” it is meant that the functional gate structure is locateddirectly above a topmost surface of the semiconductor fin as well asadjacent two vertical sidewalls of the semiconductor fin. The term“functional gate structure” is used throughout the present applicationas a permanent gate structure used to control output current (i.e., flowof carriers in the channel) of a semiconducting device throughelectrical or magnetic fields. The functional gate structure (44, 46)can be formed utilizing a gate first process or a gate last process.

In a gate first process, at least one functional gate structure isformed prior to forming the source and drain regions. The at least onefunctional gate structure can be formed by deposition of a gate materialstack and then patterning the gate material stack by lithography andetching.

The at least one functional gate structure includes a gate dielectricmaterial portion 44 and a gate conductor portion 46. While theembodiment that is illustrated discloses that the gate dielectricmaterial portion 44 and the gate conductor portion 46 are the same inthe pFET device region 22 and the nFET device region 24, it is alsopossible to form a gate dielectric material portion and/or a gateelectrode portion in the nFET device region that is different from thegate dielectric material portion and/or the gate electrode portion inthe pFET device region. In such embodiments, conventional block masktechnology can be used in forming the different gate dielectric materialportion and/or different gate electrode portion in each of the deviceregions.

In the embodiment illustrated in the drawings, the gate dielectricmaterial portion 44 is present on three surfaces (i.e., the two verticalsidewalls and the topmost surface) of each germanium-containingsemiconductor fin 40 and three surfaces of each second III-V compoundsemiconductor fin 36 (i.e., the two vertical sidewalls and the topmostsurface). In other embodiments, and when a remaining portion of thefirst sacrificial spacer 32P is still present atop each semiconductorfin, the gate dielectric material portion is located only on the twovertical sidewalls of the semiconductor fins.

The gate dielectric material portion 44 includes any gate dielectricmaterial. In one embodiment, the gate dielectric material that providesthe gate dielectric material portion 44 can be a semiconductor oxide, asemiconductor nitride, and/or a semiconductor oxynitride. In oneexample, the gate dielectric material that provides each gate dielectricmaterial portion 44 can be composed of silicon dioxide, silicon nitrideand/or silicon oxynitride. In another embodiment of the presentapplication, the gate dielectric material that provides the gatedielectric material portion 44 may include at least a dielectric metaloxide. Exemplary dielectric metal oxides that can be used as the gatedielectric material that provides the gate dielectric material portion44 include, but are not limited to, HfO₂, ZrO₂, La₂O₃, Al₂O₃, TiO₂,SrTiO₃, LaAlO₃, Y₂O₃, HfO_(x)N_(y), ZrO_(x)N_(y), La₂O_(x)N_(y),Al₂O_(x)N_(y), TiO_(x)N_(y), SrTiO_(x)N_(y), LaAlO_(x)N_(y),Y₂O_(x)N_(y), SiON, SiN_(x), a silicate thereof, and an alloy thereof.Each value of x is independently from 0.5 to 3 and each value of y isindependently from 0 to 2. In some embodiments, a multilayered gatedielectric structure comprising different gate dielectric materials,e.g., silicon dioxide, and a dielectric metal oxide can be formed andused as the gate dielectric material that provides the gate dielectricmaterial portion 44.

In some embodiments of the present application, the gate dielectricmaterial that provides the gate dielectric material portion 44 can beformed by a deposition technique such as, for example, chemical vapordeposition (CVD), plasma enhanced chemical vapor deposition (PECVD),physical vapor deposition (PVD), sputtering, or atomic layer deposition.In another embodiment of the present application, the gate dielectricmaterial that provides the gate dielectric material portion 44 can beformed by a thermal growth technique such as, for example, thermaloxidation and/or thermal nitridation. In yet a further embodiment of thepresent application, a combination of a deposition and thermal growthmay be used in forming a multilayered gate dielectric structure.

In one embodiment of the present application, the gate dielectricmaterial that provides the gate dielectric material portion 44 can havea thickness in a range from 1 nm to 10 nm. Other thicknesses that arelesser than or greater than the aforementioned thickness range can alsobe employed for the gate dielectric material that provides the gatedielectric material portion 44.

The gate conductor portion 46 may comprise any conductive material.Examples of conductive materials that can provide each gate conductorportion 46 include, but are not limited to, doped polysilicon, dopedsilicon germanium, an elemental metal (e.g., tungsten, titanium,tantalum, aluminum, nickel, ruthenium, palladium and platinum), an alloyof at least two elemental metals, an elemental metal nitride (e.g.,tungsten nitride, aluminum nitride, and titanium nitride), ormultilayered combinations thereof. In one embodiment, an entirety of theconductive material that provides the gate conductor portion 46 iscomprised of a doped polysilicon or doped polysilicon germanium. Inanother embodiment, a lower portion of the conductive material thatprovides the gate conductor portion 46 is comprised a conductivematerial other than doped polysilicon or doped polysilicon germanium,and an upper portion of the conductive material that provides the gateconductor portion 46 is comprised of doped polysilicon or doped silicongermanium.

The conductive material that provides the gate conductor portion 46 canbe formed utilizing a deposition process including, for example,chemical vapor deposition (CVD), plasma enhanced chemical vapordeposition (PECVD), physical vapor deposition (PVD), sputtering, atomiclayer deposition (ALD) or other like deposition processes. In oneembodiment, the conductive material that provides the gate conductorportion 46 has a thickness from 1 nm to 100 nm. Other thicknesses thatare lesser than or greater than the aforementioned thickness range canalso be employed for the conductive material that provides the gateconductor portion 46.

As mentioned above, the functional gate structure can be formed by firstproviding a material stack of, from bottom to top, a gate dielectricmaterial and a conductive material. In some embodiments, block masktechnology may be used to form different gate dielectric materialsand/or conductive materials within the various device regions. Followingthe formation of the material stack, the material stack can be patternedby lithography and etching. Lithography can include forming aphotoresist (not shown) on the topmost surface of the conductivematerial of the material stack, exposing the photoresist to a desiredpattern of radiation, and then developing the exposed photoresist with aresist developer to provide a patterned photoresist atop the materialstack. At least one etch is then employed which transfers the patternfrom the patterned photoresist into the various materials of thematerial stack. In one embodiment, the etch used for pattern transfermay include a dry etch process such as, for example, reactive ionetching, plasma etching, ion beam etching or laser ablation. In anotherembodiment, the etch used for pattern transfer may include a wetchemical etchant such as, for example, KOH (potassium hydroxide). In yetanother embodiment, a combination of a dry etch and a wet chemical etchmay be used to transfer the pattern. After transferring the pattern intothe material layers, the patterned photoresist can be removed utilizinga resist stripping process such as, for example, ashing. Afterpatterning the gate material stack, a functional gate structureincluding gate dielectric material portion 44 and a gate conductorportion 46 is formed.

At this point of the present application, conventional processing can beused to form a dielectric spacer on the exposed sidewalls of thefunctional gate structure, and thereafter dopants can be introduced intoportions of each germanium-containing semiconductor fin 40 and eachIII-V compound semiconductor fin 36 not including the functional gatestructure and dielectric spacer utilizing techniques that are well knownto those skilled in the art to form the source regions and the drainregions of each finFET device. The source regions in each various deviceregion may then be merged utilizing an epitaxial growth process.

In some embodiments, a gate last process (not specifically shown) can beused in forming the at least one functional gate structure. In such anembodiment, a sacrificial gate structure (not shown) is first formedstraddling each semiconductor fin within the various device regions. Theterm “sacrificial gate structure” is used throughout the presentapplication to denote a material that serves as a placeholder structurefor a functional gate structure to be subsequently formed.

The sacrificial gate structure can be formed by first providing ablanket layer of a sacrificial gate material. The blanket layer ofsacrificial gate material can be formed, for example, by chemical vapordeposition or plasma enhanced chemical vapor deposition. The thicknessof the blanket layer of sacrificial gate material can be from 50 nm to300 nm, although lesser and greater thicknesses can also be employed.The blanket layer of sacrificial gate material can include any materialthat can be selectively removed from the structure during a subsequentlyperformed etching process. In one embodiment, the blanket layer ofsacrificial gate material may be composed of polysilicon. In anotherembodiment of the present application, the blanket layer of sacrificialgate material may be composed of a metal such as, for example, Al, W, orCu. After providing the blanket layer of sacrificial gate material, theblanket layer of sacrificial gate material can be patterned bylithography and etching so as to form the sacrificial gate structures.

Next, a dielectric spacer can be optionally formed on sidewalls of eachsacrificial gate structure. The source and drain regions (and thecorresponding extension regions) can be formed after formation of theeither the sacrificial gate structure or spacer formation. Next, adielectric material is provided that has an upper surface that is planarto each sacrificial gate structure. Then, each sacrificial gatestructure can be replaced with a functional gate structure as definedabove.

Referring now to FIG. 16, there is illustrated the exemplarysemiconductor structure of FIG. 13 after forming a second sacrificialspacer 48 on sidewall surfaces of each germanium-containingsemiconductor fin 40 within the pFET device region 22 and on sidewallsurfaces of each III-V compound semiconductor fin 36 within the nFETdevice region 24. The second sacrificial spacer 48 can include one ofthe dielectric spacer materials mentioned above for providing the firstsacrificial spacer 32. In one embodiment, each second sacrificial spacer48 comprises a same spacer dielectric material as the first sacrificialspacer 32. In another embodiment, each second sacrificial spacer 48comprises a spacer dielectric material that is different from the spacerdielectric material utilizing in providing the first sacrificial spacer32. The second sacrificial spacer 48 can be formed utilizing thetechnique mentioned above in forming the first sacrificial spacer 32. Insome embodiments of the present application, each second sacrificialspacer 48 has a topmost surface that is coplanar with a topmost surfaceof the remaining portion of the first sacrificial spacer 32P that ispresent atop each semiconductor fin 36, 40. Each second sacrificialspacer 48 has a base, i.e., bottommost surface, which is locateddirectly on a surface of the remaining germanium-containing materialportion 16P.

Referring now to FIGS. 17A-17B, there are illustrated the exemplarysemiconductor structure of FIG. 16 after forming an anchoring structure50, and after performing an etch to undercut each germanium-containingsemiconductor fin 40 within the pFET device region 22 and each III-Vcompound semiconductor fin 36 within the nFET device region 24; in FIG.17B, element 52 denotes the undercut region that is formed in thepresent application. In the top-down view provided in FIG. 17A, only theanchoring structure 50 and the germanium-containing semiconductor fins40, and the III-V compound semiconductor fins 36 are shown for clarity.

The anchoring structure 50 is located on each width-wise end segment ofeach semiconductor fin 36, 40 and is in contact with a portion of theremaining germanium-containing material portion 16P. The anchoringstructure 50 comprises a dielectric material that is different in termsof its composition from that of the dielectric spacer material thatprovides at least the second sacrificial spacer 48. In one embodiment ofthe present application, the anchoring structure 50 is comprised of adielectric oxide such as, for example, silicon dioxide. The anchoringstructure 50 can be formed by deposition of a dielectric material andthen the deposited dielectric material can be patterned by lithographyand etching to form the structure shown in FIGS. 17A-17B.

After providing the anchoring structure 50, an etch is performed thatundercuts each germanium-containing semiconductor fin 40 within the pFETdevice region 22 and each III-V compound semiconductor fin 36 within thenFET device region 24. The etch removes the remaininggermanium-containing semiconductor material portion 16P and theunderlying intermediate layer of germanium 14L from beneath eachgermanium-containing semiconductor fin 40 and beneath each III-Vcompound semiconductor fin 36. Thus, the etch exposes a topmost surfaceof the underlying silicon material layer 12L. In the drawings, element14P denotes a remaining portion of the intermediate germanium layer 14,while element 16P′ represents another remaining portion of thegermanium-containing semiconductor portion 16P. The etch used to formthe undercut region 52 includes an etching process that selectiveremoves germanium as compared to dielectric materials. In one example,diluted aqueous hydrogen peroxide (H₂O₂) can be used to provide theundercut region 52 beneath each of the semiconductor fins.

Referring now to FIG. 18, there is illustrated the exemplarysemiconductor structure of FIGS. 17A-17B after forming an isolationstructure 54 in the undercut area 52 located beneath eachgermanium-containing semiconductor fin 40 within the pFET device region22 and each III-V compound semiconductor fin 36 within the nFET deviceregion 24. As is shown, a portion of the isolation structure 54 contactsa bottommost surface of each germanium-containing semiconductor fin 40and a bottommost surface of each III-V compound semiconductor fin 36.

The isolation structure 54 may comprise a dielectric material such as,for example, an oxide. In one embodiment, the isolation structurecomprising silicon dioxide. The dielectric material that provides theisolation structure 54 may be the same or different, typically the same,as the dielectric material used to provide the anchoring structure 50.The isolation structure 54 can be formed by deposition of a dielectricmaterial and then the deposited dielectric material can be recessedutilizing an etch back process.

Referring now to FIG. 19, there is illustrated the exemplarysemiconductor structure of FIG. 18 after removing each secondsacrificial spacer 48. Each second sacrificial spacer 48 can be removedby an etch process. In one example, a reactive ion etch can be used toremove each second sacrificial spacer 48. In some embodiments (notshown), this etch may also remove the remaining first sacrificial spacer32P from the topmost surface of each of the semiconductor fins 36, 40.Each of the germanium-containing semiconductor fins 40 and each of theIII-V compound semiconductor fins 36 are spaced at a first pitch, p.Also, the nearest neighboring pair of germanium-containing semiconductorfin 40 and III-V compound semiconductor fin 36 is spaced at the samepitch (i.e., the first pitch) as the pitch between individual samesemiconductor material fins. The pitch can be between 20 nm and 100 nm.In the present application, the pitch (i.e. first pitch) is defined asthe space between fin plus fin width.

Referring now to FIG. 20, there is illustrated the exemplarysemiconductor structure of FIG. 19 after removing a remaining portion ofthe first sacrificial spacer 32P from atop each germanium-containingsemiconductor fin 40 within the pFET device region 22 and from atop eachIII-V compound semiconductor fin 36 within the nFET device region 24,and forming a functional gate structure (44,46) straddling eachgermanium-containing semiconductor fin 40 within the pFET device region22 and each III-V compound semiconductor fin 36 within the nFET deviceregion 24. In some embodiments, the first remaining portion of the firstsacrificial spacer 32P can remain atop each of the semiconductor. Theremoval of remaining portion of the first sacrificial spacer 32P can beperformed by etching or by a planarization process.

Each functional gate structure (44, 46) can include a gate dielectricmaterial portion 44, and a gate conductor portion 46 as defined aboveand each functional gate structure can be formed utilizing a gate-firstor gate-last process as also described above.

Referring now to FIG. 21, there is illustrated the exemplarysemiconductor structure of FIG. 8 after forming another block mask 56 ata boundary between the pFET device region 22 and the nFET device region24, and then forming a plurality of germanium-containing fins 40 withinthe pFET device region 22 and a plurality of III-V compoundsemiconductor fins 36 in the nFET device region 24. The another blockmask 56 may include one of block mask materials mentioned above informing the first block mask 34. Also, the another block mask 56 can beformed utilizing a technique mentioned above in forming the first blockmask 34. In this embodiment, the another block mask protects an area ofthe structure in which other devices, such as, for example, a tunnel FETcan be formed.

After forming the another block mask 56, process continues in formingthe plurality of germanium-containing fins 40 within the pFET deviceregion 22 and the plurality of III-V compound semiconductor fins 36 inthe nFET device region 24 as described above. After forming thesemiconductor fins, the process disclosed in FIGS. 13-15 or FIGS. 16-20can be performed.

While the present application has been particularly shown and describedwith respect to various embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formsand details may be made without departing from the spirit and scope ofthe present application. It is therefore intended that the presentapplication not be limited to the exact forms and details described andillustrated, but fall within the scope of the appended claims.

What is claimed as new is:
 1. A method of forming a semiconductorstructure comprising: providing a plurality of mandrel structures on arelaxed germanium-containing material layer of a semiconductor materialstack containing a pFET device region and an nFET device region; formingrecessed openings into said relaxed germanium-containing material layerwithin said nFET device region of said semiconductor material stack, butnot said pFET device region; forming an III-V compound semiconductormaterial plug in each recessed opening; forming sacrificial spacers onsidewall surfaces of each mandrel structures within said pFET deviceregion and said nFET device region; removing each mandrel structure fromsaid pFET device region and said nFET device region; and forming aplurality of germanium-containing semiconductor fins in exposed portionsof said relaxed germanium-containing material layer in said pFET deviceregion, and a plurality of III-V compound semiconductor fins in exposedportions of said III-V compound semiconductor material plug in said nFETdevice region utilizing said sacrificial spacers as an etch mask,wherein said plurality of germanium-containing semiconductor fins isformed prior to said plurality of III-V compound semiconductor fins andcomprises: forming a first block mask protecting said nFET deviceregion; etching exposed portions of said relaxed germanium-containingmaterial layer in said pFET device region utilizing said sacrificialspacers as an etch mask to provide said plurality ofgermanium-containing semiconductor fins; removing said first block mask;forming a second block mask protecting said pFET device region; etchingexposed portions of said III-V compound semiconductor material plugutilizing said sacrificial spacers as an etch mask to provide saidplurality of III-V compound semiconductor fins; and removing said secondblock mask.
 2. The method of claim 1, wherein said providing saidplurality of mandrel structures on said relaxed germanium-containingmaterial layer of said semiconductor material stack comprises: firstepitaxially growing an intermediate layer of germanium on a surface of asilicon material layer; second epitaxially growing said relaxedgermanium-containing material layer on said intermediate layer ofgermanium; forming a mandrel material layer on a topmost surface of saidrelaxed germanium-containing material layer; and patterning said mandrelmaterial layer by lithography and etching.
 3. The method of claim 1,wherein said forming said recessed openings into said relaxedgermanium-containing material layer within said nFET device region ofsaid semiconductor material stack, but not said pFET device regioncomprises: forming a hard mask material portion over each mandrelstructure and exposed portions of said relaxed germanium-containingmaterial layer within said pFET device region of said semiconductormaterial stack; and etching exposed portions of said relaxedgermanium-containing material layer within said nFET device region ofsaid semiconductor material stack utilizing each mandrel structure insaid nFET device region as an etch mask.
 4. The method of claim 3,wherein said etching of said exposed portions of said relaxedgermanium-containing material layer within said nFET device region ofsaid semiconductor material stack provides recessed openings havingsidewall surfaces that undercut a portion of said mandrel structures insaid nFET device region.
 5. The method of claim 1, wherein said formingsaid III-V compound semiconductor material plug in each recessed openingcomprises an epitaxial growth process.
 6. The method of claim 5, whereinsaid epitaxial growth process comprises an aspect ratio trappingprocess.
 7. The method of claim 1, further comprising forming a localisolation structure between each germanium-containing semiconductor finand each III-V compound semiconductor fin.
 8. The method of claim 1,further comprising forming a functional gate structure straddling eachgermanium-containing semiconductor fin and each III-V compoundsemiconductor fin.
 9. The method of claim 1, further comprisingundercutting each germanium-containing semiconductor fin and each III-Vcompound semiconductor fin by removing a portion of said semiconductormaterial stack from beneath each germanium-containing semiconductor finand each III-V compound semiconductor fin and forming an isolationstructure in an undercut region provided by said undercutting, whereinprior to undercutting an anchoring structure is formed along edge-wiseend segments of each germanium-containing semiconductor fin and eachIII-V compound semiconductor fin.
 10. The method of claim 9, furthercomprising forming a functional gate structure straddling eachgermanium-containing semiconductor fin and each III-V compoundsemiconductor fins.